The present invention relates to a new and distinct cultivar of Physocarpus opulifolius and will be referred to hereafter by its cultivar name, ‘ZLEYel2’. Physocarpus opulifolius is a deciduous shrub grown for landscape use. The key objective within the Physocarpus opulifolius breeding program I initiated in St. Paul, Minn. was to develop new Physocarpus opulifolius cultivars that are compact growing, well-branched, healthy, and possess colorful foliage. One objective has been to produce a cultivar with the yellow-green foliage color of Physocarpus opulifolius ‘Dart's Gold’ (not patented) and the compact, well-branched growth habit and small foliage of cultivated ninebark such as Physocarpus opulifolius as var. nanus (not patented) or its descendant Physocarpus opulifolius ‘Donna May’ (disclosed in U.S. Plant Pat. No. 22,634).
‘ZLEYel2’ originated by crossing Physocarpus opulifolius ‘Donna May’ as the female parent and Physocarpus opulifolius ‘Dart's Gold’ as the male parent. The pollination that led to the population of seedlings from which ‘ZLEYel2’ was identified occurred in June 2011. The seeds of this population germinated during the winter of 2011/2012 indoors under florescent lights in St. Paul, Minn. Seedlings were grown in containers during their first year. At the end of the first growing season, seedlings with attractive foliage color, relatively compact growth habits, and powdery mildew resistance were retained. Selections were planted outside during their second growing season. ‘ZLEYel2’ was recognized as a highly desirable genotype among this seedling population during the summer of 2012. ‘ZLEYel2’ was planted outside in 2013 and was first asexually propagated using semi-hardwood stem cuttings in the spring of 2013. I have found that the characteristics of ‘ZLEYel2’ are stable and true to type over successive generations of vegetative propagation.
‘ZLEYel2’ was unique from the other ninebark seedlings because of its small yellow-green foliage and compact, very well-branched plant habit. ‘ZLEYel2’ first flowered in 2014 with attractive blush-white flowers that are abundant and attractive against the yellow-green foliage. As follicles develop in full sun, they are a coral pink to red color for about a month and provide additional ornamental value.